Ethereum Prysm client bug causes validator participation to drop by 25%, nearly resulting in loss of finality

According to ChainCatcher, exchange monitoring revealed that shortly after the Fusaka network upgrade, the participation of validators on the Ethereum network dropped sharply and a large number of voting nodes went offline due to a bug in the Prysm consensus client.

Prysm officially announced on Thursday that its v7.0 client unnecessarily generated old states when processing outdated Attestations, causing nodes to fail to operate properly. Developers advised users to temporarily start the client with the “--disable-last-epoch-targets” flag as a temporary solution.

Data from Beaconcha.in shows that at Epoch 411,448, the network's Sync Participation and Voting Participation dropped to 75% and 74.7% respectively. Voting participation fell by 25%, leaving less than 9 percentage points from the two-thirds supermajority (66.6%) required to maintain network finality.

The magnitude of this drop in voting participation roughly matches the validator share of the Prysm consensus client, indicating that Attestation failures were likely concentrated among Prysm validators. Previously, Prysm’s share had reached as high as 68.1%. As of press time, the current Epoch (411,712) on the Ethereum network shows voting participation has recovered to nearly 99%, and sync participation has reached 97%, indicating the network has recovered.

Current MigaLabs data shows Lighthouse still accounts for 52.55% of consensus nodes, with Prysm ranking second at 18%. Ethereum educator Anthony Sassano stated that if Lighthouse had encountered this bug, the network would have lost finality.